Re: [PATCH] autofs4: Use wait_event_killable

[Ian Kent]

On 20/03/18 03:16, Matthew Wilcox wrote:
> From: Matthew Wilcox <mawil...@microsoft.com>

Hi Matthew,

> 
> This playing with signals to allow only fatal signals appears to predate
> the introduction of wait_event_killable(), and I'm fairly sure that
> wait_event_killable is what was meant to happen here.

Predates is an understatement, this is really, really old code.
Do I need to forward this to Al or Andrew?

> 
> Signed-off-by: Matthew Wilcox <mawil...@microsoft.com>
Signed-off-by: Ian Kent <ra...@themaw.net>
> ---
>  fs/autofs4/waitq.c | 27 +--------------------------
>  1 file changed, 1 insertion(+), 26 deletions(-)
> 
> diff --git a/fs/autofs4/waitq.c b/fs/autofs4/waitq.c
> index a0c57c37fa21..c160e9b3aa0f 100644
> --- a/fs/autofs4/waitq.c
> +++ b/fs/autofs4/waitq.c
> @@ -19,9 +19,6 @@
>   */
>  static autofs_wqt_t autofs4_next_wait_queue = 1;
>  
> -/* These are the signals we allow interrupting a pending mount */
> -#define SHUTDOWN_SIGS        (sigmask(SIGKILL) | sigmask(SIGINT) | 
> sigmask(SIGQUIT))
> -
>  void autofs4_catatonic_mode(struct autofs_sb_info *sbi)
>  {
>       struct autofs_wait_queue *wq, *nwq;
> @@ -486,29 +483,7 @@ int autofs4_wait(struct autofs_sb_info *sbi,
>        * wq->name.name is NULL iff the lock is already released
>        * or the mount has been made catatonic.
>        */
> -     if (wq->name.name) {
> -             /* Block all but "shutdown" signals while waiting */
> -             unsigned long shutdown_sigs_mask;
> -             unsigned long irqflags;
> -             sigset_t oldset;
> -
> -             spin_lock_irqsave(&current->sighand->siglock, irqflags);
> -             oldset = current->blocked;
> -             shutdown_sigs_mask = SHUTDOWN_SIGS & ~oldset.sig[0];
> -             siginitsetinv(&current->blocked, shutdown_sigs_mask);
> -             recalc_sigpending();
> -             spin_unlock_irqrestore(&current->sighand->siglock, irqflags);
> -
> -             wait_event_interruptible(wq->queue, wq->name.name == NULL);
> -
> -             spin_lock_irqsave(&current->sighand->siglock, irqflags);
> -             current->blocked = oldset;
> -             recalc_sigpending();
> -             spin_unlock_irqrestore(&current->sighand->siglock, irqflags);
> -     } else {
> -             pr_debug("skipped sleeping\n");
> -     }
> -
> +     wait_event_killable(wq->queue, wq->name.name == NULL);

The wait event code looks like this will wake up on most any unmasked signal.
But my assumption is that TASK_KILLABLE tasks are only forwarded specific
signals ...

Is that right or am I missing something?

>       status = wq->status;
>  
>       /*
>